11. White ink
The surface of the ink layer during printing and printing is milky white, resulting in cloud-like whitish loss of light. Occurs when the volatile ink is printed. When it is severe, it will completely lose its luster. Micropores will appear on the ink layer and the adhesion will decrease.
the reason:
(1) The air humidity in the workplace is too high;
(2) The organic solvent used has a low boiling point and is too volatile;
(3) The humidity of the substrate is too high;
(4) Ink and thinner in water;
(5) The solvent and diluent do not match, causing the resin to appear white on the surface of the ink layer.
The first three conditions cause the water vapor in the air to condense on the surface of the substrate, penetrate into the ink layer and cause whitening.
Prevention:
(1) The ambient temperature of the work site is preferably 15 to 25°C and the relative humidity is not higher than 70%;
(2) Select organic solvents with higher boiling points and lower volatilization rates, or add moisture-proof agents;
(3) Before printing, the substrate should be dried with a hair dryer. The temperature of the hot air is about 10°C higher than the ambient temperature.
(4) Prevent the moisture in the solvent and air from entering the printing ink layer;
(5) Prevent resin from depositing during film formation.